Image warping, also know as 3-Dimensional (3-D) rendering or texture mapping, can be used to create a 3-D projection from an original 2-Dimensional (2-D) first image. Image warping is used to create visual effects in different visual media including film, television 3D graphics and computer displays. It can be expressed as the process of mapping pixels from a source sample grid to a target sample grid. Typically, the target grid is sampled at a different frequency than the source grid. In general, the output grid does not vary in a constant manner with respect to The input grid. The variations from pixel to pixel between the source grid and the target grid can make the process of image warping extremely complex.
Several systems and methods for image warping are known. Detailed discussions of prior art image warping and systems are discussed in Wolberg, George, “Separable Image Warping: Implications and Techniques”, Phd. Thesis, Department of Computer Science, Columbia University, New York, 1990 and “Digital Image Warping”, IEE Computer Society Press, Los Alomos, Calif., 1990. The prior art systems described in these documents are typically complicated and expensive to implement due to the large number of computations required.
U.S. Pat. No. 5,594,676 herein referred to as the '676 patent) titled “Digital Image Warping System”, issued to Greggain et al discloses a particular prior art implementation for image warping. The '676 patent overcomes some of the problems of the prior art by using an intermediate grid, upsampled from the source grid, but having corresponding pixels to the target grid. In this manner, the source pixels are first mapped to the upsampled grid, and then readily mapped to the target grid.
Despite offering certain advantages over the prior art, the '676 patent still presents a relatively complicated solution because it requires an intermediate, upsampled grid. Upsampling requires extra circuitry and processing steps in order to achieve the desired digital image warping result. Furthermore, upsampling introduces distortion and can soften the image, which are often undesirable effects.
Therefore, it is an object of the present invention to obviate or mitigate at least some of the above mentioned disadvantages.